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Understanding Tesla Autopilot

A few Tesla vehicles have had accidents with Autopilot enabled recently, and I’ve gotten countless questions about these incidents and the nature of Autopilot from people who aren’t Tesla owners. Tesla and the media haven’t clearly communicated what these features do (and don’t do) to the public, so I’ll try to help in whatever small way I can as a Model S owner for a few months so far.

I apologize in advance if I get any technical details wrong about these features. Authoritative information is hard to find, and these features change and evolve often.

Tesla’s autonomous features today, all somewhat grouped under or involved in “Autopilot”:

Automatic emergency braking: This always-on feature will sense if you’re approaching another car or obstacle too quickly and loudly alert you. If you don’t apply the brakes yourself, the car will automatically brake to some degree. This is a common feature in luxury cars today and seems to be a clear safety win.

Autopark: Reverses into parking spots on demand. This is also becoming a common feature on other cars, and seems reasonably safe as long as you watch out for pedestrians. I use it regularly for parallel parking and it works well.

Summon: This feature lets you command the car, from outside of it, to very slowly drive itself into or out of a garage or parking space. It’s disabled by default and requires multiple steps to enable and engage (nobody could do this accidentally). The potential damage from failures is likely limited to car body or garage damage, not major bodily harm, due to the very slow movement and ultrasonic parking sensors. I haven’t used it yet — I don’t think the small benefit is worth the risk.

Adaptive cruise control: Like normal cruise control, but with a forward radar (augmented by the camera) to maintain a safe distance from the car ahead of you, automatically slowing down or even stopping as necessary. It’s almost like automated driving, but you still steer, and you’re responsible for obeying signs and signals. This feature is also available on many luxury cars today, and Tesla’s is the best one I’ve used yet, so I use it all the time. It bears most of the same risks as any cruise control, but the chances of rear-ending the car ahead of you are greatly reduced, and it may even be safer than manual driving in low-speed stop-and-go traffic. I’m a huge fan of this feature.

Autosteer, which people probably mean by “Autopilot”: Really just one significant addition to adaptive cruise control: the car also steers itself, using the camera to detect lane markings painted on roads (a feature offered by many other cars on its own) and automatically steer to keep you roughly centered in the lane.

Autosteer is a strange feeling in practice. It literally turns the steering wheel for you, but if you take your hands off for more than a few minutes, it slows down and yells at you until you put your hands back on the wheel. It’s an odd sensation: You’ve given up control of the vehicle, but you can’t stop mimicking control, and while your attention is barely needed, you can’t safely stop paying attention.

It’s automated enough that people will stop paying attention, but it’s not good enough that they can. You could say the same about cruise control, but cruise control feels like an acceptable balance to me, whereas Autosteer feels like it’s just over the line. History will probably prove me wrong on that, but it feels a bit wrong today.

Tesla, Elon Musk, and a lot of media coverage have set expectations too high for these features. People expect Autosteer to be fully autonomous, but today’s Tesla vehicles simply don’t have the hardware or software to safely and reliably self-drive on all roads, and such an advance doesn’t feel imminent.

There’s a huge gap between Autosteer and what most people expect from a “self-driving car”. For instance, Autosteer doesn’t see signs or traffic signals, so it will happily drive through red lights or stop signs if you let it.

Most critically, Autosteer has simply not been reliable enough yet for me on anything but wide-laned, gently turning, intersection-free highways with clearly painted lines in dry weather. In my experience, using it on any other type of road — even New York’s highway-like parkways — is dangerous and unsettling, often requiring manual corrections to avoid crossing center lines or getting dangerously close to lane edges and concrete barriers.

The most reliable, useful, and defensible parts of Tesla’s “Autopilot” features today are emergency braking, Autopark, and adaptive cruise control. I’d be just as happy with my Model S if it only had those, without Summon or Autosteer.

While I like using Autosteer on long highway trips, frankly, I’m amazed that it’s legal. I don’t think it’s a big enough advance over adaptive cruise control to be worth the risks in its current implementation. I’m scared for what will happen to Tesla and the progress of autonomous driving as more people use Autosteer in situations it’s not good at, or as a complete replacement for paying attention.

If Tesla updates the software to restrict Autosteer only to interstate highways, the yelling (and possible lawsuits) from existing owners would cause short-term pain, but I think it may save a lot of reputation damage — and possibly even people’s lives — in the long run.